Exactly How A Chiropractic Adjustment Works

The Chiropractic Adjustment

A displaced or luxated vertebra is when the joint surfaces are completely separated. Subluxation is a partial or incomplete separation: one in which the articulating surfaces remain in partial contact. This latter condition is so often referred to and known by chiropractors as sub-luxation. The relationship existing between bones and nerves are so nicely adjusted that anyone of the 200 bones, more especially those of the vertebral column, cannot be displaced ever so little without impinging upon adjacent nerves. Pressure on nerves excites, agitates, creates an excess of molecular vibration, whose effects, when local, are known as inflammation, when general, as fever. A subluxation does not restrain or liberate vital energy. Vital energy is expressed in functional activity. A subluxation may impinge against nerves, the transmitting channel may increase or decrease the momentum of impulses, not energy.

“According to BJ Palmer, a subluxation represents a displaced bone that's impinged on a nerve, which interferes with the transmission of vital nerve energy (or, more specifically, ‘mental impulses.’)” 

For over hundred years, chiropractors have explained chiropractic medicine by teaching patients and the medical community that bones compress which irritate spinal nerves. The ensuing nervous system dysfunctions have negative effects on the function of peripheral nervous systems, central nervous systems and patients’ overall ability to maintain homeostasis. Essentially, they go into states of dis-ease.  These discussions were in large part due to the teachings of D.D. Palmer and B.J. Palmer as previously cited. Based on the results rendered in chiropractic offices across the country and in a patient-driven model of success, the general consensus in both private practice and chiropractic academia had been to maintain status quo and simply teach what has worked in the absence of conclusive evidence, particularly in light of a lack of serious governmental funding and support for chiropractic research.  In addition, dogma has also created blinders for many, as evidence evolves to further chiropractic and its understanding, application and expansion.

Research has been published and has begun to verify D.D. and B.J. Palmer’s hypotheses were correct. While clarifying the specific physiological mechanisms related to chiropractic’s ability to alleviate pain.  As a result of initially studying pain mechanisms, contemporary research has also begun to set the foundation for understanding why chiropractic works with systemic and autonomic dysfunction and potential disease treatment through the adjustment – central nervous system connection. It is the understanding of that connection with pain that is helping people to begin to understand the full impact of the chiropractic spinal adjustment and render the evidence to help more get well.

CENTRAL NERVOUS SYSTEM & PAIN REDUCTION

Reductions in pain sensitivity, or hypoalgesia, after spinal manipulative therapy or a chiropractic adjustment may point to a mechanism related to the central nervous system processing of pain. These findings indicate that a chiropractic spinal adjustment affects the dorsal horns at the root levels which are located in the central nervous system.  This is the beginning of the “big picture” since once we identify the mechanism by which we can positively influence the central nervous system, we can then study that process and its effects in much more depth.

One question asked, does a chiropractic adjustment cause a general response of pain sensitivity or if the response is specific to the area where adjustment is applied? For example, changes in pain sensitivity over the cervical facets following a cervical spine SMT would indicate a local and specific effect while changes in pain sensitivity in the lumbar facets following a cervical spine SMT would suggest a general effect. We observed a favorable change for increased PPT [pressure pain threshold] when measured at remote anatomical sites and a similar, but non-significant change at local anatomical sites. These findings lend support to a possible general effect of SMT beyond the effect expected at the local region of SMT application.

The adjustment mechanism is theorized to result from both spinal cord mediated mechanisms and the brain. A recent model of the mechanisms of manual therapy suggests changes in pain related to SMT result from an interaction of neurophysiological responses related to the peripheral nervous system and the central nervous system at the spinal and supraspinal level.

This demonstrates that chiropractic adjustment influences the peripheral nervous system and the central nervous system.  

1. ACTIVATION OF BRAIN & DESCENDING NERVE PATHWAYS BEYOND AREAS TREATED
2. CHIROPRACTIC ADJUSTMENT VS. SPINAL MOBILIZATION

Manual therapy has clinically shown to boost pressure pain thresholds (i.e., decrease sensitivity) in both symptomatic and asymptomatic subjects. Cervical spinal manipulation has been shown to result in unilateral as well as bilateral mechanical hypoalgesia. Compared with no manual therapy, oscillatory spinal manual therapy at T12 and L4 produced significantly higher paraspinal pain thresholds at T6, L1, and L3 in individuals with rheumatoid arthritis. The immediate and widespread hypoalgesia associated with manual therapy treatments has been attributed to alterations in peripheral and/or central pain processing including activation of descending pain inhibitory systems.

Manual therapy triggers the central nervous system which affects areas around those being treated. 

Clinical studies show spinal manipulation or an adjustment alters the central processing of mechanical stimuli. This is proven by an increased pressure pain threshold and decreased pain sensitivity in asymptomatic and symptomatic subjects following manipulation.

The thalamus also regulates states of sleep and wakefulness which plays a major role in regulating arousal, the level of awareness, and activity (Thalamus http://en.wikipedia.org/wiki/Thalamus).

Therefore, a chiropractic adjustment reduces pain through the thalamus.  In addition, with current knowledge of chiropractic adjustment effecting the thalamus, we can begin to offer an explanation of how the first historically reported chiropractic adjustment by D.D. Palmer helped Harvey Lilard regain his hearing.

CHIROPRACTIC REDUCES PAIN IN MULTIPLE REGIONS DUE TO LOCAL AND CNS STIMULATION

Significant changes were observed on sensory parameters, supporting the hypothesis of centrally mediated effects of a single adjustment. This suggests that the chiropractic spinal adjustment affects the nociceptors and the mechanoreceptors at the joint level causing central modulation of an effect at the cord and/or brain level(s) and pain reductions in multiple areas as a result.

AN ADJUSTMENT WILL CREATE HIGHER FUNCTION IN CORTICAL AREAS

MT or manual therapy/chiropractic adjustment reduce pain intensity and pain sensitivity. it is reasonable to assume that the underlying therapeutic effect of MT is likely to include a higher cortical component.

In other words, thoracic adjustments produced direct and measureable effects on the central nervous system across multiple regions, which in the case of the responsible for the processing of emotion (cingulate cortex, aka limbic cortex) are regarding the insular cortex which also responsible for regulating emotion as well has homeostasis. The motor cortex is involved in the planning and execution of voluntary movements, the amygdala’s primary function is memory and decision making (also part of the limbic system), the somatosensory cortex is involved in processing the sense of touch (remember the homunculus) and, finally, the periaqueductal gray is responsible for descending pain modulation (the brain regulating the processing of painful stimuli).

Brain Region	Function
Cingulate Cortex	Emotions, learning, motivation, memory
Insular Cortex	Consciousness, homeostasis, perception, motor control, self-awareness, cognitive function
Motor Cortex	Voluntary movements
Amygdala Cortex	Memory, decision making, emotional reactions
Somatosensory Cortex	Proprio and mechano-reception, touch, temperature, pain of the skin, epithelial, skeletal muscle, bones, joints, internal organs and cardiovascular systems
Periaqueductal Gray	Ascending and descending spinothalamtic tracts carrying pain and temperature fibers

The global effects of a chiropractic adjustment simply put, the processing of pain may be modulated or regulated from an external force without the use of pharmacy or surgery? Pain is deeply tied to the most primitive regions of the central nervous system and it appears (as chiropractors have observed clinically for 116 years) that therapeutically speaking, we can have an influence on these higher centers with little or no side-effects.

Chiropractic spinal adjustments create functional changes in multiple regions of the brain. In addition, this has far reaching effects in setting the foundation for understanding how the adjustment works in systemic and possibly autonomic changes by being able to measure and reproduce functional changes within the brain as direct sequellae.

1. MUSCLE IMPAIRMENT CREATES CNS ALTERATIONS & THE NECESSITY FOR BOTH SHORT-TERM & LONG-TERM CHIROPRACTIC CARE
2. ADJUSTMENTS WORK – SPINAL MOBILIZATION DOES NOT

What this means is that there are observable changes in the function of the central nervous system seen in patients with musculoskeletal conditions.  That is something that chiropractors have observed clinically and shows the medical necessity for chiropractic care for both short and long term management as well as in the prevention of pain syndromes.

Evidence suggests that muscle damage occurs early in spinal complaints, and that such muscle damage does not automatically resolve even when pain symptoms improve. This has led some authors to suggest that the deficits in proprioception and motor control, rather than the pain itself, may be the main factors defining the clinical picture and chronicity of various chronic pain conditions.

This evidence suggests that chiropractic manipulation may have a positive neuromodulatory effect on the central nervous system, and this may play a role in the effect it has in the treatment of neck pain.

When the input signal is no longer encoded as a result of joint dysfunction and altered afferent input, the cerebellum must adjust to new encodings that dictate the body schema and affect proper execution of the motor task.

The significance is that it suggests that chiropractic adjustments improve neck dysfunction, and through plasty changes in the cerebellum, there is resultant motor learning and increased function. 

CONCLUSION

Chiropractic adjustments influence the peripheral nervous system and the central nervous system. In the central nervous system, chiropractic spinal adjustments reduce pain by effecting the thalamus and descending central pain pathways.

The areas of the brain affected by chiropractic adjustments effect the following functions: emotions, learning, motivation, memory, consciousness, homeostasis, perception, motor control, self-awareness, cognitive function, voluntary movements, decision making, touch, temperature, pain of the skin- epithelial tissue-skeletal muscles-bones-internal organs and cardiovascular system.